Gas-engine cam



E. V. MYERS.

GAS ENGINE CAM.

APPLICATION FILED MAR. a, 1920.

Patented Nov. 2, 1920.

INVENTOR M KM By A llorneys,

warren stares EUGENE V. MYERS, OF EAST ORANGE, NEW JERSEY.

GAS-ENGINE CAM.

T 0 all to 710m it may concern Be it known that I, EUGENE V. MYERS, acitizen of the United States of America, residing in East Orange, in thecounty of Essex and State of New Jersey, have invented certain new anduseful Improvements in Gas-Engine Cams, of which the following is aspecification.

This invention relates to cams for explosive engines, and particularlythe fourcycle type.

In this type of engine the cam being mounted on a half speed shaft hasat the maximum a quarter of its circumference devoted to the rise, dwelland fall of the cam. I-Ieretofore such cams have been made as small incircumference as would give the necessary upward movement of the valvethe exhaust stroke. As a result the capacity of the intake and exhaustvalves has been much less than that which is necessary to secure thefull power of the engine especially when the engine is working at itsmost efiicient speed, the intake wire drawing and the exhaust buildingup a pressure within the cylinder, with the result of imperfectscavenging. To overcome this difficulty, it has been customary in themodern practice to build the engine with two exhaust valves and twointake valves, thereby doubling the capacity of the inlet port and theoutlet ort. p I have found that if the cam be largely increased in size,say to two, three or four times its customary size, very much improvedresults can be obtained. That is to say, the dwell of the cam can beincreased to fifty or more degrees out of a possible ninety, therebymoving the valve quickly to wide-open position, and holding it inwideopen position for a relatively long time during the stroke of thepiston and promptly closing it. The capacity of the valve is hence muchincreased.

Specification of Letters Patent.

Application filed March 3, 1920.

Patented Nov. 2, 1920.

Serial No. 362,929.

tice that the rise B and drop D shall be tangential to the circle of thecam. These are continued in a tangential direction until the proper liftof the cam is reached. They are then connected with a curved portionwhich constitutes the dwell C. In the drawmg I have illustrated thedwell C as rather abnormally long from the standpoint of actualpractice, it being shorter in many cases than that illustrated. Theangle E in this construction is about 18, and it follows that the l1fterrod is operated to its full height for about the same period during therevolution of the cam shaft.

Referring now to the cam provided by the invention, which is designatedby the letter A, it will be observed that the rise B and drop D are alsostruck tangentially from theperiphery of the cam. In point of linearextent it will be found that the rise and drop are longer than the riseand drop on the cam A. In point of ascent from the periphery, it ishence evident that the valve rod rises a more gradual incline, or has amore gradual lift than with the cam A. The dwell C, which is of the sameheight as the dwell C, is, however, greatly increased in length, withthe result that the valve is held wide open a much longer period thanwith the cam A. In the device illustrated the angle E is approximatelyor nearly three times as great as with the cam A. Hence the valve iskept open aomuch longer period during the 90 allotted for its movement.

It is recognized that the peripheral speed of the cam A is much greaterthan that of the cam A, so that it travels past the valve rod at a muchgreater speed per linear measurement than. does the cam A. With the sametype of rise and drop, however, the incline up which the valve rodtravels is no greater than that of'the cam A; indeed, it is about 70 percent. longer. The greater speed of peripheral travel of the cam A,therefore, does not introduce any i, "Maw-k materially "greater sidethrust on the valve rod.

This result cannot be obtained with a small cam having the necessary lif7 It is obvious that the rise or drop, or either, can have any suitableshape. If it be desired to ease the drop, so as to more graduallyseat'the valve, a suitable shape can be adopted for this purpose, and itdesired, a portion of the dwell can be sacrificed for this purpose. Soalso on the rise the valve may be initiallylifted from its seat,

or its inertia overcome, at the start by a more gradual rise. Thetangential rise and drop, however, have proven to satis factory and areillustrated on this account. While I have shown and described one formof the invention, it will he understood that I have not illustrated theessential form of engine which may be of any ordinary type or the lifterrod or valve rod, since these may be of any usual or customaryconstruction.

WVhat I claim is 1 1. A valve cam for four-cycle internal combustionengines, of large dlameter, having" a rise, a dwell and a drop arranged.Within 90 of the cam shaft, and having a dwell of approximately 50 ofsuch shaft 2. A valve cam for four-cycle internal combustion engines, oflarge diameter, having a rise, a dwell, and a drop arranged within 90 ofthe cam shaft, and having a dwell of approximately 50 of such shaft,

the rise being substantially tangential to signed my name. 7

Y EUGLNE V. MYERS.

